Thaw shrimp, if frozen. Rinse shrimp and pat dry. Cut shrimp in half lengthwise. Set aside.
For sauce, in a small mixing bowl stir together the water, wine vinegar, soy sauce, catsup, cornstarch, sugar, chicken bouillon granules, and ground red pepper. Set aside.
If using rice sticks, in a medium saucepan cook the rice sticks in boiling water for 1 to 2 minutes or just until tender. Drain and keep warm.
Pour cooking oil into a wok or large skillet. (Add more oil as necessary during cooking.) Preheat over medium-high heat. Stir-fry the garlic and ginger in hot oil for 15 seconds. Add bok choy, if using. Stir-fry for 1-1/2 minutes. Add the green onions and yellow or red pepper; stir-fry about 1-1/2 minutes more or until the vegetables are crisp-tender. Remove the vegetables from the wok.
Add the shrimp to the hot wok or skillet. Stir-fry for 2 to 3 minutes or until shrimp turn opaque. Push shrimp from the center of wok.
Stir the sauce. Add the sauce to center of the wok. Cook and stir until thickened and bubbly. Return vegetables to the wok. Add spinach, if using. Stir all ingredients together to coat with sauce. Cook and stir about 1 minute more or until heated through. Serve over hot cooked rice sticks or rice. Makes 2 servings.